Clay products for vitreous slips



Patented Jan. 22, 1935 v a Y UNITED STATES PATENT OFFICE 1,988,800 CLAY PRODUCTS FOR VITREOU S SLIPS Charles J. Kinzie, Charles H. Commons, Jr., and Donald S. Hake, Niagara Falls, N. Y., assignors to The Titanium Alloy Manufacturing -Company, New York, N. Y., a corporation of Maine No Drawing. Application November 26, 1932,

Serial No. 644,486

20 Claims. (Cl- 106'36.2)

Our invention relates to improved methods in desire to improve their appearance by increasing the preparation of enamel slips for use in vitreous "the lustre and by reducing blemishes in surface enameling and glazing, and particularly to imthrough use of pu'r er raw materials and more proved clay products to be used in setting up such advanced operating procedures. In case of the enamel slips whereby the finely ground particles generally used enamels (non acid resisting), one s of the enamel frit or glass maybe maintained of the common causes of blemishes, such as black uniformly in suspension; also to improved specks, etc., is due to the clay used to suspendthe methods of producing such clay substances as will milled glass in the vehicle (water). According to serve advantageously in such enamel slips by the present practices the amount of clay commonly addition to the clay of water-insoluble hydroxides used is essential for this purpose.

. v of metals thereby to improve its plastic properties. Our invention comprises, among other things, Wealso partially dry the improved clay products the discovery of satisfactory means of suspendbefore use in such a way as to remove substaning' the enamel glass par'ticles'either resulting in tially all the water, while retaining the desired the elimination of the clay addition, or in its subplastic properties when our products are emstantial reduction in amount whereby threefold 15 bodied in the mill mix in forming the enamel advantages will result viz: '(1) The applied slip. enamel film would mature in shorter time or at In the practice of vitreous enameling and glazlower temperature; (2) the lustre would be in ing, particularly the vitreous enameling on metal creased (as practically all inorganic mill addiby h w t proc s in which the na el or glaze tions detract from lustre); (3) there would be a 20 flit is milled With Water, y, and pa ifi complete or partial elimination of troubles caused additions, it has been the practice to use from 4 by impurities introduced in the usual clay. to 8% enameling clay at the mill to assist in keep- As a result of our investigations carried on i the glass frii? Particles in Suspension along these lines, so as to effect a setting up of h lay has the eiiect of hardening the mixenamel slips by means other than the addition of 25 ture so that a hig e tempe atu e 0 a longe the usual 6% clay, we discovered that small time Of burning is q d h w u b h amounts of aluminum hydroxide were very effeceese i t am u t f ay u d b l w r d or tive, and by the use thereof, the clay addition Omitted entirely- 7 could be materially reduced with resultant econ- U. Patent 1,785,777 of December omy due to fact that enamels so set up required 30'- 0 describes and C a m methods for Setting p a lower temperature or a shorter time to mature enamel slips particularly of the acid resisting and were of a-higher lustre and of generally type, in which salts of zirconium or titanium are finer quality, used in the mill liquor, and the resulting precipi- We also discovered that there could be pretate of the metal hydrate effects a setting up of pared an improved clay product by adding alumi- '35 enamel p W the suspensieh of hit Particles num hydroxideto clay, and the resulting product, therein. when dried according to our inventionf'may be In an application f patent fi y One Of 115 used in greatly reduced amountswith the bene- June 6, 1931, Serial No. 549,125, it is disclosed that fit e have mentioned, In addition to these ad- 40 g n r y better results Were a e if vantages we found that the enamels containing 40'- i'litenillm hydroXide (Orthotitanie acid) Was P the, substantially lowered clay content were of a pared separately and freed from incidental salts purer white color, or in case of tints and stronger before adding to the enamel. colors, there was a greater purity of tone. This Such patent and application for patent readvantage was due to lowering of clay which terred particularly to the setting up 'of vitreous owing to its impurities, such as iron, etc., caused 445 enamels of the acid-resisting type, and experian undesirable discoloration in the enamel. ments performed had shown that titanium Our invention may be practiced in several ways: hydroxide had less detrimental efiect upon the and the initial step of preparing the hydrate acid resistance of the enamel as compared with compound will be first described.

aluminum hydroxide in acid resisting enamels A water soluble salt of aluminum, such as 50 For this reason aluminum hydroxide was referred potash alum (A12(SO4) 3-K2SO4.24H2O) or else to as being unsuited for this purpose. aluminum sulphate, is dissolved in water and During recent years a markedtendency has precipitated with ammonium hydroxide and is; developed in the trade toward the use of softer then well washed. Instead of alum or aluminum (lower firing) vitreous enamels together wi h sulphate there may be used a solution obtained 56 by treating acid soluble compounds of aluminum. The solution so obtained is then treated with ammonia to precipitation of the aluminum as the hydroxide. Clay might be digested with H2804, dissolved in water and then precipitated in the usual manner. In any event the precipitate is essentially freed of water soluble compounds by suitable washing, and the precipitate may then be dewatered to form a stiff paste containing about 4% residue upon ignition. There may also be included titanium or zirconium hydroxide either by having these in solution, and then precipitating same along with the aluminum, or by separately precipitating and later mixing with the aluminum hydroxide.

The aluminum hydroxide either form of' slurry or as a paste can be added to the mill charge, and the following charge will illustrate.

Parts by weight Frit 100 Alum. hydrate paste (4% A1203) 6. 25 Clay 2 Zirconium oxide 6 Water 29 Total 143.25

The charge is milled in usual manner and applied in usual manner, but may be burned on at a somewhat lower temperature or for a shorter time at the temperature commonly used.

The above procedure of application of the aluminum hydrate paste to enamel milling although practical from actual enameling standpoint entails the shipping of considerable waterwith the aluminum hydroxide. We prefer, therefore, to make our improved clay products in dry form and supply them for use to the enameler in dry form.

In the following complete example, we have referred to aluminum compounds, but other hydrates such as titanium, zirconium, calcium, etc. may be used to replace part of the aluminum. We prefer usually to have the aluminum hydroxide constitute one-half or more of the metal hydrates present, and for ordinary non-acid-resisting enamels either ground or cover coat, we prefer to work with aluminum alone for purposes of economy and simplicity.

In addition to the hydrated compounds above mentioned, there exists thepossible application of silicic acid (gelatinous), iron hydroxides, magnesium hydroxide, tin hydroxide, etc. The only limit being that the hydroxide used be active in adding to the plastic or suspending properties of the clay in setting up the enamel slips.

We may practice'our invention according to the following example.

' Example A (Improved clay for setting up enamels) Aluminum sulphate (Al(SO4)3.18I-I2O), 100 parts is dissolved in water, 14,000 parts. To this solution added NH3. The NH3 is preferably first dissolved in water andthen added to the solution of aluminum sulphate. Only enough ammonia to completely precipitate the aluminum and make the solution slightly alkaline need be used. v

The batch is washed by any suitable means to essentially free it of the ammonium sulphate.

If washing is by settling and decantation there will be a settled charge consisting of aluminum hydroxide suspended in water which can be further dewatered by suitable means such as a rotary filter, gravity filter, or centrifugal machine. The

paste obtained for this example contains aluminum hydroxide equivalent to 4% A1203 and the amount of the paste will be about 382.5 pounds. We now take 136 pounds of plastic clay, preferably Illinois Kaolin, and this is charged to a ball mill with about three hundred pounds of water. The ball mill should contain only enough balls to assistin'working up the true clay into a fine state with the water and leaving all foreign matter as larger grains or pieces. The mill is discharged and the clay slip is run through a suitably fine lawn or sieve to effect removal of any such foreign matter. In this example the 136 pounds of-clay contained 13.6 pounds of materialremaining on sieve which was discarded, leaving in the clay slip 122.4 pounds of clay.

The 382.5 pounds aluminum hydrate paste are now thoroughly incorporated into and with the clay slip, and although it can be used direct at the mill, we prefer to dry it at about 50 to 70 C. to obtain an essentially dry product which can be handled dry for packaging and storage.

The product may be also partially dried by any suitable mechanical means or may beuair dried by sun heat or in a warm room in thin layers. However if driedat too high a temperature, the aluminum hydroxide becomes inactive; for instance, if the product is dried at 110 C., it would have no value in setting up the enamel. The dried product is preferably pulverized.

A suitable product prepared by drying at 50-66" C. had substantially the following composition:--

at 950 C 22. 69

Effective products have also been prepared in which titanium and zirconium were precipitated along with the aluminum. For example, for use with enamels of the acid-resistant type, it is important to keep the percentage of aluminum down to minimum, but due tofact that aluminum hydroxide is particularly active in setting up enamels it is well to have as much of this hydroxide present as is permissible;

Satisfactory products containing aluminum and titanium hydroxides have been prepared by including sufiicient titanium salt, such as the chloride or sulphate, along with the aluminum sulphate in suflicient amount to yield about as much titanium hydroxide as there is 'of aluminum hydroxide. The product is then washed and processed as described in Example A. The aluminum hydroxide and titanium or other hydroxide can be separately'prepared and combined in any desired proportion to produce an improved clay for setting up enamels and the like.

The following mill mix example will show how the product of foregoing Example A can be used,

the ingredients being. measured parts by weight:.

Parts Frit 100 Improved clay product 3 Zirconium oxide 6 Solution of gum tragacanth containing 0.0033% G. T Water 30 Total 144 The gum'tragacanth solution is usedto maintain a satisfactory degree of dry film strength when the enamel is milled and then applied to the ware, since most enamels with this low clay addition would'in absence of. gum have a weak film upon drying and'would be subject to injury in handling of ware. This defectcan be over come by use of the adhesive solution to strengthen the bond. A trace of formaldehyde can be contained in the gum solution tokeep the charge from becoming sour when stored.

As an example illustrating the use of hydrates of metals other than aluminum, we will now give the followingin which hydrate of titanium containing some calcium and other compounds was used effectively to produce an improved clay product. I a

Example B As the first step there is prepared astock of hydroxide of metals which has the following composition: r

. Per cent Titanium oxide (TiOz) 7.21 Silica (S102) Q. 0.13 Iron oxide (F8203) 0.07 Alumina (A1203) 0.07 Zirconia (ZiOz) 0.12 Calcia (CaO) 1.00 Magnesia (MgO) 0.04

Water (H2O) Q. 91.36

This paste was obtained by precipitating the hydroxides by addition of ammonia to a water solution containing salts of the several metals, and, after the'precipitatehad been washed by settling and decantation to free of water soluble salts, was then obtained by dewatering in a centrifugal machine. a v

In the analysis, the percentages are set down as oxides, but in the paste these oxides exist as hydrated compounds. 16.75 poundsof clay, preferably Illinois kaolin, are worked up to a slip by suitable means preferably in aball mill with lbs. of water and milled fine There is then added to the clay 27 A poundsof' this heretofore described water-insoluble hydrated metal paste, and the whole is well blended by any suitable means. More water is added if necessary, and then such paste is dried at suitable temperatures to yield a dry product which is preferably disintegrated to a fine powder. This powder may be used effectively to suspend and setup enamels in same manner as the product prepared from clay and aluminum hydroxide paste which we have hereinbefore described. 7

If the presence of clay is objectionable a paste comprising ingredients according 'to the analysis given can be used alone in the following manner:

, Parts by weight Frit Q 1 100.00 I 2. s7

Hydroxide paste 102. 87 The charge is milled with'water along with coloring agents if desired, or with a white opacifier. There is added also a solution of. adhesive mate rial such as gum tragacanth to yield about 0.015%: gum based on 100 parts of frit. For most purposes, the dry product containing clay. will be best suited, but in some cases it will be advantageous to avoid use of clay entirely. The 2.8'lparts of this hydroxide paste is equivalent to 0.25% oxide material introduced as the hydroxide and based on 100 parts of frit- The hydroxide mate-:

rial can be produced in" still more concentrated formby suitable methods, but care must be taken so'as not to destroy its efiectiveness'by overheating during drying. Generally it isbest to dispense the material in paste form as we havedescribed";

an example of how our invention may be practiced with a mixture of aluminumwater-in-- soluble hydroxide in conjunction, with a hydrox ide of another metal, we willjnow set forth-the. detailed procedure tobefollowed. I V .3

Example '0 first 'step'in thisas' in'otli'er examples is tol prepare the "water-insoluble metal hydroxide which'is efiected by precipitating the hydroxides, by means of an alkali, preferably ammonium hydroxide, from a solution of the metal salts in water. The; precipitate upon washing and dewatering yields for this examplea paste contain ing the following amounts of metal hydroxide, which-although existing as the hydroxides have been calculated to the oxide basis, as follows:

.UTwenty pounds of clay are preferably ballmilled with about 100 parts of water to a' fine state, and 48.3 parts of mixed metal hydroxide paste according to theabove analysis is thor-z oughly mixed with the clay by suitable means. The charge is then dried at temperatures and for a time period sufficient to produce a partlydryproduct in which the hydroxides are in an active state for our purposes. The dried product is pref erably then disintegrated to a fine powder.

In thetwo foregoing ExamplesB-and C,-we have shown how the product may be produced from titanium hydroxide containing a substantial proportion of calcium hydroxide, and also how aluminum and titanium may be used together.

We will now set forth two examples showing how to prepare the enamel with the use of the products of our invention.

Example D illustrates the productionof a white:

enamel by use of our improved clay product.

Batch mix ggg g *Sodium zirconium silicate 7. 15 Quartz 38. 97 Borax 30. 05 Soda ash i6. 82 Sodium nitrate 3. 50 Titanium oxide. 14.00 Antimony oxide- .7. 00 Oryolite l. 00 Fluorspar 5. 00 123. 49

Sodium zirconium silicate 'oi K inzie U. S. Patent No. 1,789,311 and as used in batchesreferred to in thisv specification had the following compositioni Theseingredients .of the batch: are intimately mixed and. smelted andquenchedin water :in the usual manner to produce a white .opaque :Irit, which .would have the "following approximate composition :5

p r Percent sodiumoxidelNazo) '17 Calcium fluoride (CaFz) )5 Sodium aluminum fluoride (NazA1F6) 1 Antimony oxide (SbzOs) '7 Boric anhydride (3203)"; 11 Silica (S102)--. 41 Titanium oxide (TiOz) 14 Zirconium oxide (ZrO:) 4

This white opaque frlt may now be prepared for the wet process enameling. operation as follows:

' Parts by 1 d f weight rm; 100 Zirconium oxide 6 Improved clay product .r 3 Water about 35 Charge is milled to suitable fineness such as, for example, as represented by a 100 c. 0. sample of slip having 12 grams residue upon a 200 mesh sieve after washing the sample through the sieve with water.

The resulting slip'is appliedin usual manner v and dried and finally burned. A Second coat may be applied if desired. The result is an enamel of excellent lustre, white color, and good surface.

Example E illustrates the use of metal hydrox-,

ides (without clay) in producing a clear enamel or glaze. I

. Batch mix 3:2

Sodium zirconium silicate. 7. 08 Quartz V. 48.,52 27. 05 26. 72 Sodium nitrate. 3. 50 Titanium oxide 13. 36 126. 23

Sodium zirconium silicate of Kinzie ,8. Patent No. 1,789,311 as in Example D. I

The batch is mixed and smelted and quenched in water, to form a clear frit which has the following approximate composition:

Percent Sodium oxide (NazO) 22.31 Boric anhydride (B203) 9.90 Silica (S102 i 50.47 Titanium oxide (T102) 13.36 Zirconimn oxide (ZrOz) 3.96

To produce a clear glaze 100 parts of this frit is mixed with.2.8'7 parts of metal hydrate paste of Example B together with 30-parts of water or enough to make a charge of good wet milling consistency. This charge is then milled .to desired fineness which in this example may be very fine. that is, milled to point where practically, all frit particles are finer than 325mesh. The slip may be applied over suitable objects and burned to produce a thin vitreous coating. A coloring agent or stain may be used and is preferably added at the mill to give a desired coloror tint to the final coating.

In the appended claims we use the termwaterinsoluble metal hydroxide or hydroxides to embrace the hydratesor hydroxides of all metals we have mentioned that are active in aiding or increasing the plastic or suspending properties of the clay in setting up of enamel slips, such as aluminum, titanium, zirconium, calcium, iron, magnesium, and tin, or mixtures thereof.

We claim as our invention:

1. The method oi makinga clay product for use in vitreous enamelingand glazing which comprises mixing plastic clay and a water-insoluble metal hydroxide and then partly drying the resulting mixture.

2. The method of making a clay product for use in vitreous enameling and glazing which comprises mixing plastic clay anda water-insoluble metal hydroxide and then partly drying and pulverizing the resulting mixture.

3,. The method of making a clay product for usein vitreous enameling and glazing which comprises mixing plastic clay and a mixture of waterinsoluble metal hydroxides and then partly dryingthe resulting mixture.

" 4. The method of'making a clay product for use in vitreous enameling and glazing which comprises mixing plastic clay and a mixture of waterprises preparing a gelatinous fiocculent metal hy-- droxide precipitate, adding sameto a plastic clay slip to combine therewith, and then partly drying-the resulting charge.

'7. The method of making a clay product for use in vitreous enameling and glazing which comprises preparing a gelatinous fiocculent metal hydroxide precipitate, adding same to a plastic clay slip to combine therewith, and then partly drying the resulting charge at a temperature from 50 to 70 C.

8. The method of making a'clay product for use in vitreous enameling and glazing which comprises preparing gelatinous fiocculent aluminum hydroxide precipitate, adding same to a plastic clay slip to combine therewith, and then partly drying the resulting charge.

9. The method of making a clay product for use in vitreous enameling and glazing which comprises preparing gelatinous fiocculent aluminum hydroxide precipitate admixed with other waterinsoluble metal hydroxides, adding same to a plastic clay slip to combine therewith, and then partly drying the resulting charge.

10. The method of making a clay product for use in vitreous enameling and glazing which comprises impregnating a plastic clay slip with gelatinous fiocculent aluminum hydroxide precipitate, then partly drying the mixture at a temperature below C., and finally pulverizing the resulting dried mass.

11. The method of making a clay product for inous flocculent aluminum hydroxide precipitate containing aluminum calculated as alumina about 4 per cent, then partly drying the mixture at a temperature below 110 C., and finally pulverizing the resulting dried mass.

12. A clay product for use in setting up an enamel slip for vitreous enameling and glazing which consists of a plastic clay slip impregnated with a water-insoluble metal hydroxide.

13. A clay product for use in setting up an enamel slip for vitreous enameling and glazing which consists of a plastic clay slip impregnated with a mixture of water-insoluble metal hydroxides.

14. A clay product for use in setting up an enamel slip for vitreous enameling and glazing which consists of a plastic clay slip impregnated with a mixture of water-insoluble metal hydroxides in which aluminum hydroxide is the major ingredient.

15. A clay product for use in setting up an enamel slip for vitreous enameling and glazing characterized as being a partly dried substance comprising plastic clay impregnated with a water-insoluble metal hydroxide.

16. A clay product for use in setting up an enamel slip for vitreous enameling and glazing characterized as being a partly dried powdered substance comprising plastic clay impregnated with a water-insoluble metal hydroxide.

7 17. The method of preparing vitreous enameling and glazing slips which comprises setting up the said slips by adding a clay product impregnated with a water-insoluble metal hydroxide to the charge at the mill.

18. The method of preparing vitreous enameling and glazing slips which comprises setting up the said slips by adding a clay product impregnated with a water-insoluble metal hydroxide and mixed with an adhesive to the charge at the mill.

19. The method of preparing vitreous enameling and glazing slips which comprises setting up the said slips by adding thereto a clay product impregnated with a mixture of gelatinous flocculent water-insoluble metal hydroxides to hold said glass particles in suspension therein.

20. The method of preparing vitreous enameling and glazing slips which comprises setting up the said slips by adding thereto a gelatinous flocculent water-insoluble metal hydroxide paste mixed with an adhesive to hold said glass particles in suspension therein.

CHARLES J. KINZIE. CHARLES H. COMMONS, JR. DONALD S. HAKE. 

